The present invention relates generally to the field of subscription communication systems and, more particularly, is directed to an information display scheme which simplifies the display of information to subscribers of a subscription communication system.
Subscription communications systems, such as television and special events programming, have gained wide spread acceptance as an efficient way of providing a vast selection of information and entertainment programming to the public. Such systems normally charge a fixed monthly service fee which entitles the subscriber to receive regular programming for the entire month. Many systems also provide a "movie channel" or a "special events channel" for an additional fee. Though a subscriber may wish to view only one or two movies or special events during the course of a month, he must nevertheless pay the full additional fee. Payment of a full fee where only a fraction of the service is utilized is uneconomical and often results in a majority of subscribers signing up to receive only regular programming. Thus other services are not sufficiently supported to provide quality programming.
A subscription television system should include provisions for a subscriber not only to select which channels he wishes to receive, but also to select which programs on a particular channel he wishes to view. In order to achieve maximum flexibility, the subscriber should also be permitted to make this selection at anytime without having to indicate to the broadcaster or system operator beforehand that he wishes to view a particular program. Ideally, the system should make all programming available to the subscriber and permit him to select and pay for only those programs that he actually views. This concept is often called "pay-per-program".
In a subscription television system having a pay-per-program feature, the system operator must be continuously informed of the programs selected for viewing by the subscriber for proper billing. Thus, such systems require an up-link or some form of communication from the subscriber to the system operator. Subscribers could, of course, maintain a log of all programs viewed and periodically send the log to the system operator for billing purposes. The integrity of such a billing procedure is suspect, however, and is impractical for a system having many subscribers. On-line feedback to the system operator of programs selected for viewing by the subscriber is also possible but such feedback provisions greatly complicate and increase the cost of the system.
In subscription television systems having a pay-per-program feature, the subscriber must also be kept apprised of his account status. Such information could be provided by a conventional teletext system where all the digital pulses which represent data are transmitted from the headend of the system on lines of the vertical blanking interval of the television signals. This data represents alphanumeric and graphical information which may be selectively displayed to the subscriber using a television receiver adapted for teletext reception. Typically, the subscriber requests a particular magazine page of information for display using a remote keypad interfaced to the teletext receiver. The receiver waits until the requested page is transmitted in the channel then captures the information in a page storage buffer. The contents of the buffer are displayed through a character generator onto the television screen.
In teletext systems known in the prior art, no significant modifications are made to the transmitted pages prior to their display on the screen other than, perhaps, the addition of a page number in a fixed position on certain pages. In particular, conventional teletext systems do not provide for the addition of locally generated information by the receiver which might change the meaning or the interpretation of the transmitted information. Thus, information that is specifically directed to a particular subscriber, for example billing information, must always be completely generated at the headend or distributor end for down loading to the subscriber. This adds to the complexity of the system. Thus, in systems having a pay-per-program feature, means must still be provided for communicating to the system operator a listing of programs watched by the subscriber. Such a requirement further increases the complexity and cost of the system.